A matatu conductor was shot dead and four others seriously injured at the Odeon matatu termini in the city centre on Sunday morning.
Three young men had boarded a bus and sat on the rear seat. Two of them started beating their colleague, prompting the driver, Mr Kevin Macharia, to order them out of the bus.
One of them drew a pistol and shot Mr Robert Kamadi, the matatu conductor, on the chest and also shot the driver on the forehead.
The gunman also shot two other passengers, Mr Kennedy Gathuma Chege and John Njoroge Ngige on the right leg and left leg respectively.
One of the suspects who was being beaten by his colleagues was also shot on the pelvis.
The five victims were rushed to the Kenyatta National Hospital where the matatu conductor died while undergoing treatment.
The vehicle, belonging to the Star Bus Company, was towed to the Central police station.
Elsewhere, independent investigations have been launched into the fatal shooting of a robbery suspect who is said to have attempted to escape from a police vehicle as he was being transferred from Njathaini to Kinoo police post on Sunday afternoon.
According to the police, the deceased, Mr Joseph Kibai, jumped out of the police car and was challenged to stop but he defied the orders.
He was pursued up to Kanyariri area where he was shot on the left thigh. He was then arrested and taken to the Kenyatta National Hospital where he was pronounced dead on arrival.